The invention relates to a gas charging head for pneumatically pressurizing a vehicle suspension fluid spring or damper such as an air spring, a shock absorber or a McPherson strut, and more particularly relates to a gas charging head which mechanically deflects a seal for introducing gas under pressure to the damping chambers of a suspension damper.
Heretofore, shock absorbers and struts have been pressurized by drilling a hole in the outer wall of the shock cylinder. After pressurizing the cylinder through the drilled passage, the passage is sealed by pressing a plug or ball into the drilled passage. Alternatively, the passage may be sealed by welding after the passage has been closed by the plug.
This method requires several operations such as drilling and welding which, at best, impose additional expense and the chance that metal chips or weld contaminants may be introduced into the damper assembly.
Another method of pressurizing vehicle dampers utilizes excessively high gas pressure over the piston rod seal to displace the seal and force the gas past the seal and into the chamber. Such a method makes control of the final pressure level within the damper rather difficult. The final internal pressure depends on many variables such as, the preload on the seal by the retention spring of the damper, the interface between the sealing face of the seal and the piston rod, as well as other variables.
It is therefore an object of the present invention to provide an improved gas charging apparatus for use with vehicle dampers, struts or fluid springs.
It is yet another object of the present invention to provide a charging head for use with vehicle dampers which easily controls the final internal gas pressure level within the damper body.